The invention relates to power control circuits, and in particular, to a power control circuit that will reduce power to a user device for a preselected time.
A hot melt adhesive system is mentioned throughout this application. However, it should be understood that applicants do not intend to limit the scope of available protection by this example.
Typically, a hot melt adhesive system comprises an electrically heated tank, one or more electrically heated hoses, and electrically heated guns corresponding to the hoses. Solid hot melt adhesive is placed in the tank and melted. The molten hot melt adhesive, at operating temperature, is pumped through the hose(s) and into the gun(s). Molten hot melt adhesive is then dispensed by the gun(s).
Generally speaking, when hot melt adhesives are held in the system at operating temperatures for extended periods of non-use, the hot melt adhesive may degrade. Degradation of molten hot melt adhesive may be retarded if the adhesive is kept at a temperature lower than the operating temperature but higher than the melting point. Thus, it would be advantageous to provide a power control unit that will allow for the reduction of the temperature of the molten adhesive during periods of non-use.
In manufacturing situations, oftentimes the operator knows approximately how long the period of non-use will be. For example, if over the lunch hour the gun is not used, the operator knows that the period of non-use will be about one hour. In order to minimize the time that the operator must wait on the system to reach operating temperature after the operator returns from lunch, it would be advantageous to provide a power control unit that would reduce the temperature of the molten adhesive over most of a period of non-use and yet allow the system to be at the operating temperature when the period of non-use is over.
At other times the period of non-use may not be known. Consequently, it would be advantageous to provide a power control unit that can reduce the molten adhesive to a sub-operating temperature for an indefinite period of time.
It can be expected that a user of a hot melt adhesive system may sometimes wish to use a power control unit and other times not use the unit. The unit can be placed in an "off" condition in which the power supplied to the system is unimpeded. Further, the unit is a self-contained module that is positioned between the power source (e.g. electrical outlet) and the system. The unit plugs into the outlet and the system plugs into the power unit. It is thus a very easy job to remove the power unit from the hot melt system.